(a) Field of the Invention
The present invention relates to an antenna for transmitting and receiving radio frequencies. More specifically, the present invention relates to an antenna for transmitting and receiving radio frequencies so as to be used for a mobile communication terminal that operates in two frequency bands and to easily set resonance points.
(b) Description of the Related Art
Present mobile communication services share identical frequency bands by differing modulation methods or use different frequency bands like the case of cellular phones that operate at 824 to 894 MHz and personal communication services (PCS) that operate at 1.75 to 1.87 GHz.
Conventional antennas that use the above-noted frequency bands comprise helical antennas which are installed on an upper part, of portable wireless devices and on which a helical conductor is wound, and whip antennas which penetrate the helical antennas. In the case the whip antenna is withdrawn from the helical antenna, the whip conventional antenna is used after being connected to the helical antenna.
When the resonance points are needed to be set, a gap of the helical conductor of the helical antenna is varied or a diameter of the helical antenna is sequentially varied.
Since it is difficult to set the resonance points of the resonance frequency and it is not easy to assemble the helical conductor to which the resonance point is already set, precision degrees and productivity are decreased.
When withdrawing the whip antenna from the helical antenna and using the whip antenna, since the whip antenna is electrically connected to the helical antenna, the performance of the whip antenna becomes lower because of a coupling effect.
Also, conventional feeding is performed after a feeder and a part of the helical conductor are contacted, and since this configuration has a small contact area with the feeder, electrical signals may not be stably supplied because of contact problems. In particular, this configuration can be a problem in that a small outer shock generates a short state between the feeder and the helical conductor.
It is an object of the present invention to provide a wireless transmitting and receiving antenna for quickly and accurately setting the resonance point of the resonance frequency using a simple technical configuration so as to increase productivity, setting the resonance point of a wide resonance frequency band, and electrically separating the whip antenna and the helical antenna so as to not influence the helical antenna when the whip antenna is withdrawn from the helical antenna and used.
In one aspect of the present invention, a wireless transmitting and receiving antenna comprises a bobbin of insulation material; a helical conductor spirally wound on the bobbin; a matching bar inserted into a cavity of the bobbin, maintaining a predetermined gap with the helical conductor and setting a resonance point; and a feeder supplying signals to the helical conductor.
The matching bar is made of a conductor, is cylindrical, and has a cavity in the center of the matching bar in a lengthwise direction.
The bobbin is manufactured according to a molding process while the matching bar is inserted into the bobbin.
In another aspect of the present invention, a wireless transmitting and receiving antenna comprises a bobbin made of insulation material and having a first penetration cavity in the center of the bobbin in a lengthwise direction; a first antenna comprising a helical conductor spirally wound on the bobbin and having a resonance frequency, and a matching bar inserted into the cavity of the bobbin, made of a. conductor and. providing a, second penetration cavity. in the direction identical with that of the first penetration cavity, a feeder positioned at one part of the bobbin so as to supply signals to the helical conductor, and a second antenna comprising: a rod inserted into the penetration cavities of the bobbin and the matching bar, moving between the penetration cavities in a slipping manner, and wrapped with the insulation material; a conduction material combined with the outer part of the rod, and electrically connecting the feeder and the helical conductor when the rod is inserted into the penetration cavities; and a stopper which is made of a conductor, is positioned at the lower part of the rod so that when the rod is withdrawn from the penetration cavity the movement of the stopper is limited, and is contacted to the feeder so as to supply signals to the rod.
There is provided an insulation pad for disconnecting the electrical contact between the first and second antennas when the first antenna is drawn from the second antenna.
In a further aspect of the present invention, a wireless transmitting and receiving antenna comprises a bobbin made of insulation material and having a first penetration cavity in the center of the bobbin in the lengthwise direction; a first antenna comprising a helical conductor spirally wound on the bobbin and having a resonance frequency, and a matching bar inserted into the cavity of the bobbin, made of a conductor and providing a second penetration cavity in the direction identical with that of the first penetration cavity; a feeder insulated with the helical conductor, combined to an lower part of the bobbin, providing a third penetration cavity in the direction identical with that of the first penetration cavity, and contacting the matching bar so as to supply electrical signals, and a tension spring wherein a second antenna comprising a rod is inserted into the penetration cavities of the bobbin and the matching bar, moving in the penetration cavities in a slipping manner, being wrapped with the insulation material, comprising a cap and a conductive stopper for limiting the movements in the upward and downward directions, with the tension spring maintaining a predetermined position after the second antenna is moved and being made of a conductor.